We report measurements of the decays B -→Dmore » $$+\atop{s}$$K -ℓ -$$\bar{v}$$ ℓin a data sample containing 657×10 6B$$\bar{B}$$ pairs collected with the Belle detector at the KEKB asymmetric-energy e +e - collider. We observe a signal with a significance of 6σ for the combined Ds and Ds* modes and find the first evidence of the B -→D$$+\atop{s}$$K -ℓ -v ℓ decay with a significance of 3.4σ. We measure the following branching fractions: B(B -→Ds -K -ℓ -v ℓ)=(0.30±0.09(stat)$$+0.11\atop{-0.08}$$(syst))×10 -3 and B(B-→D$$*+\atop{s}$$ +K -ℓ -v ℓ)=(0.59±0.12(stat)±0.15(syst))×10 -3 and set an upper limit B(B -→D$$+*\atop{s}$$ +K -ℓ -v ℓ)<0.56×10 -3 at the 90% confidence level. We also present the first measurement of the D$$+\atop{s}$$K - invariant mass distribution in these decays, which is dominated by a prominent peak around 2.6 GeV/c 2.« less